Filter for continuous filtration of liquids containing solids in a closed cylindrical vessel

Abstract

Filter for continuous filtration of liquids containing solids in a closed cylindrical vessel with a pressure difference between the liquid to be filtered and the filtrate, with disks which are formed by hollow filter sectors and supported at a distance from one another on a driven horizontal hollow shaft normal to the shaft, with filter beds on both sides of every filter sector and a hollow space located between the latter allowing the filtrate to flow out through the hollow shaft, and with devices which are movably pressed against on both sides of every filter disk for removing and discharging solids from the filter beds forming the outer sides of the filter disks and for cleaning these filter beds, wherein every device for removing and discharging solids from and cleaning the filter beds is formed by a closed hollow box unit which is completely surrounded by the liquid to be filtered and has a plurality of chambers which are separated from one another, wherein every chamber has at least one inlet gap comprehending the entire radius of the filter disk and at least one of the chambers contacts the respective filter bed so as to be sealed relative to it.

What is claimed is: 
     
       1. In a filter for continuous filtration of liquids containing solids in a closed cylindrical vessel with filter disks which are formed by a plurality of hollow filter sectors and supported at a distance from one another on a horizontal hollow shaft normal to the shaft, with filter plates on both sides of every filter sector and a hollow space located between the filter plates allowing the filtrate to flow out through the hollow shaft, and with devices which are disposed along both sides of every filter disk for removing and discharging solids from filter plates forming outer sides of the filter disks and for cleaning these filter plates, wherein every device for removing and discharging solids from and cleaning the filter plates is formed by a closed hollow box unit which is completely surrounded by the liquid to be filtered and has a plurality of chambers which are separated from one another, wherein every chamber has at least one inlet gap extending over the entire radius of the filter disk and at least one of the chambers contacts the respective filter plate so as to be sealed relative to it, the improvement comprising that: support means in the hollow space of each said filter sector engaging inner sides of the filter plates;   wherein said filter plates are formed of a sintered microporous material;   wherein the filter plates of each sector include an outer circumferential edge, a radially inner circumferential edge, and a pair of space apart radial edges, a cover disposed between the filter plates along the outer circumferential edges thereof, wherein said cover is concentrically connected to said shaft with a pair of sector supports which are disposed between the filter plates along the respective radial edges thereof, said outer circumferential edges and said radial edges including slots formed therein with first pressing strips disposed in said slots, a first plurality of fastening screws extending through said filter plates, first pressing strips, and cover for sealingly clamping said filter plates against said cover, a second plurality of screws extending through said filter plates, first pressing strips, and sector supports for sealingly clamping said filter plates against said sector supports, a pair of shaft receiving rings connected to said shaft and sealingly receiving the respective inner circumferential edges of said filter plates, second pressing strips arranged on the outer surface of said filter plates along the inner circumferential edges thereof for sealingly pressing said filter plates against the respective shaft receiving rings, and a third plurality of screws extending through said second pressing strips and filter plates for sealingly holding said filter plates against said shaft receiving rings;   wherein each said chamber defines a scraper for scraping solids from outer surfaces of said filter plates;   sealing strips disposed on said box units between adjacent said chambers and contacting said filter plates for sealing each said chamber from an adjacent said chamber;   wherein each said box unit extends radially along outer sides of the respective filter disk and has front wall slanted with respect to an adjacent filter plate down to a gap opening located as an inlet to a solids collecting space defined by one of said chambers the respective box unit;   wherein one of said chambers is a spray chamber, means for ventilating said spray chamber including a pipe connecting the spray chamber to the outside atmosphere, said spray chamber further including spray nozzles for directing rise water against said filter plate and means for defining a rinse water outlet;   wherein one of said chambers is a backwash chamber disposed adjacent an upstream side of said spray chamber;   wherein one of said chambers is a vacuum duct disposed adjacent a downstream side of said spray chamber; and,   means for connecting a vacuum source to said backwash chamber and said vacuum duct, whereby a vacuum within said backwash chamber and said vacuum duct forces said sealing strips against the respective filter plate to seal said spray chamber from a surrounding pressurized suspension in the filter vessel.   
     
     
       2. The filter according to claim 1, wherein the filter plates are formed of a sintered polymeric plastic material and have a porosity of 0.5 to 200 microns. 
     
     
       3. The filter according to claim 2, wherein the filter plate comprises a sintered microporous surface having a porosity of 0.5 to 200 microns and a coarse supporting body having a porosity of 10 to 200 microns. 
     
     
       4. The filter according to claim 1, wherein the filter plates are formed of a sintered metal powder material and have a porosity of 0.5 to 200 microns. 
     
     
       5. The filter according to claim 2, wherein the filter plate comprises a microporous sintered surface having a porosity of 0.5 to 200 microns and a coarse supporting body having a porosity of 10 to 200 microns. 
     
     
       6. The filter according to claim 1, wherein the filter plate has at its outer side at least one additional ceramic filter layer supported on a ground porous metal layer, wherein said filter layer has a porosity of between 0.05 and 50 microns. 
     
     
       7. The filter according to claim 1, wherein the filter plate has at the outer side at least one additional microporous filter layer of polymeric plastic having a porosity of between 0.05 and 50 microns. 
     
     
       8. The filter according to claim 1, wherein the plane, pressure-tight filter plate is produced from composite-layer sieves with coarse supporting body material and a filter layer having a porosity of 0.5 and 50 microns. 
     
     
       9. The filter according to claim 1, wherein the filter plates are provided over the entire surface area within the hollow spaces of the disks between two inwardly facing sides of the filter plates with pressure-resistant spiral springs which are arranged relative to one another at respective staggered angles in the circumferential direction of the disks. 
     
     
       10. The filter according to claim 1, wherein a conveyor screw for discharging solids is disposed inside the solid collecting space, said conveyor being arranged in proximity to an parallel to the outer side of the respective filter plate. 
     
     
       11. The filter according to claim 1, wherein the filter bed is deformed slightly so as to be sucked into the vacuum duct and backwash chamber due to the vacuum force. 
     
     
       12. The filter according to claim 1, wherein the filter beds are produced from a microporous plastics mixture of different material having the same particle size. 
     
     
       13. The filter according to claim 1, wherein the microporous filter plates are produced from identical plastics material with at least two different particle sizes. 
     
     
       14. The filter according to claim 1, wherein the filter beds are produced from at least two different materials and at least two different particle sizes.